Chlorofluorocarbon compounds are commonly used is working fluids in a variety of refrigeration equipment. Chlorofluorocarbon compounds are conventionally stored in any one of a group of commercially available pressure vessels. A safety valve is provided on such vessels in order to preclude the generation of internal pressures in excess of the pressure rating of the vessel. The safety valve opens if the internal pressure within the refrigerant vessel exceeds a predetermined maximum pressure. The predetermined maximum pressure is lower than the maximum pressure rating of the vessel. In order to avoid generating internal pressures which would trigger the safety valve, the amount of refrigerant that is introduced to the refrigerant vessel is controlled. Typically, a quantity of refrigerant fluid sufficient to fill approximately 80% of the internal volume of the vessel is introduced to the vessel. The 80% fill level allows for safe operating pressures under the worst case conditions of filling the vessel at a relatively low temperature, e.g. about 25.degree. F. and then shipping or storing the vessel at a relatively high temperature, e.g. up to about 130.degree. F.
Conventionally, refrigerant vessels are filled by weight. Weighing a pressure vessel and its contents requires a cumbersome apparatus. The requirements of weighing a pressure vessel and its contents becomes particularly onerous when filling refrigerant vessels in the field, e.g. during a refrigerant recovery process as described in U.S. Pat. No. 4,766,733.
Accordingly, it is an object of the present invention to provide a fill control valve for refrigerant vessels which permits the filling of said vessels without requiring weighing of the vessel.
It is another object of the present invention to provide a fill control valve which is mechanical and does not require the use of electricity for operation.
It is a further object of the present invention to provide a fill control valve which may be used with standard refrigerant vessel flow control valves.
The above and other objects and advantages of the present invention will become apparent to those skilled in the art when considered with the following discussion.